Today i arrived at a customers home to check their unit and to give them a second opinion. First AC company condemned the condensing unit stating compressor has bad Valves. When i arrived found condenser coil plugged solid with dirt. Contactor contacts burnt. Unit is a 5 ton R22 split system with a scroll compressor. After a good cleaning unit began to cool fine. How do i check for bad valves??
How to test Compressor Valves
Junior1983
1 - 17 of 17 Posts
Joined
·
576 Posts
Today i arrived at a customers home to check their unit and to give them a second opinion. First AC company condemned the condensing unit stating compressor has bad Valves. When i arrived found condenser coil plugged solid with dirt. Contactor contacts burnt. Unit is a 5 ton R22 split system with a scroll compressor. After a good cleaning unit began to cool fine. How do i check for bad valves??
Joined
·
956 Posts
You should be able to determine if the valves are leaking by the operating pressures.
Scrolls don't have valves. Atleast not in the way I would call valves.
A scroll may have a warped head, but it would still run. Probably wouldn't notice it, other than by sound.
Starts to tick. Kinda like a recip.
A scroll could have the head break off the shaft. But then it just pulls low amps and no compression.
It's really sink or swim.
Joined
·
576 Posts
My suction pressure was 70psi High side 280. Ambient temp 90deg
Joined
·
576 Posts
Thanks for the info. I knew i read somewhere scrolls dont have valves
Joined
·
956 Posts
I am so guilty of only reading your title to you thread. 
TXV issue?
TXV issue?
Joined
·
10,766 Posts
Reminds me of some second opinion visits I have made where previous techs warned the customer that they suggest replacing their AC system because "the compressor is tired"? WTF. Same goes with the bad or weak valves on a scroll, just moronic sales-tech terminology.
You want to start posting in the PRO forums I am more than happy to get deep into diagnosing hermetic compressor valves and other issues.
You want to start posting in the PRO forums I am more than happy to get deep into diagnosing hermetic compressor valves and other issues.
Joined
·
2,457 Posts
Assuming no air in the system. By the pressures and temps you posted I'd say some cleaning is still needed of both the Evaporator and Condenser
Previous guy was inept or sales commission corrupt?
Worn valves will give you low amps for a full load and low performance. TXV system will be normalish SSH and low TD. Easiest way to check a tin can without compressor valves is to disconnect outdoor fan, head pressure should skyrocket, bad valves will be slow or never hit 450 psi, more like stay around 300-350 psi for example. Comp may only take 5 sec to go from 300 to 450 psi, although the time will vary a little depending upon the load. Experience this test with good compressors in the past and you will get a better feel for the timing.
Worn valves will give you low amps for a full load and low performance. TXV system will be normalish SSH and low TD. Easiest way to check a tin can without compressor valves is to disconnect outdoor fan, head pressure should skyrocket, bad valves will be slow or never hit 450 psi, more like stay around 300-350 psi for example. Comp may only take 5 sec to go from 300 to 450 psi, although the time will vary a little depending upon the load. Experience this test with good compressors in the past and you will get a better feel for the timing.
Joined
·
1,664 Posts
Pump it down and see if it gets there and stays there. Fairly simple...
Joined
·
32,723 Posts
This should be in Pro Residential, and not in the open Commercial......
..we can be more help that way.
..we can be more help that way.
^^^^^^This.:grin2:
Maybe it was running high head pressure from the dirty condenser, and the bypass valve inside the compressor opened.
So when the other tech got there, the compressor was running but pressures where equal, so he thought it was a bad compressor.
So when the other tech got there, the compressor was running but pressures where equal, so he thought it was a bad compressor.
Maybe so, good call
1 - 17 of 17 Posts
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
